Machine and process for cutting hobs, worms, and the like.



w. CANNELL. MACHINE AND PROCESS FOR CUTTING HOBS, WORMS, AND THE LIKE.

APPLICATION FILED DEC. 5 I914.

1 ,27 1 ,662. Pamnted July 9, 1918.

3 SHEETS-SHEET I.

HUI IHIUIW i" INVENTOI'? W. CANNELL.

' MACHINE AND PROCESS FOR cumm; H088, worms, AND THE LIKE.

APPLICATION FILED DEC. 5 1914. 1,271,662. Patented July 9,191&

3 SHETS-SHET 2.

M 8858 727%? Qwe/ INVENTOR W. CANNELL.

MACHINE AND PROCESS FOR cumm; HOBS, wows, AND THE LIKE.

APPLICATION FILED DEC. 5 IBM 1 ,271,662. Patented July 9, 1918.

3 SHEETS--SHEET 3.

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mm. A, 1%

UNITED STATES PATENT OFFICE.

WILLIAM CANNELL, OF SPRINGFIELD, MASSACHUSETTS, ASSIGNOR TO BAUSHMACHINE TOOL COMPANY, A CORPORATION OF MASSACHUSETTS.

MACHINE AND PROCESS FOR CUTTING HOBS, WORMS, AND THE LIKE.

To all whom it may concern:

Be it known that I, WILLIAM CANNELL a subject of Great Britain, andaresident of Springfield, Massachusetts, have invented certain new anduseful Improvements in Machines and Processes for Cutting Hobs, Worms,and the like, of which the follow: Hg is a specification.

This invention provides an improved style of worm 0r hob for cuttingworm gears and the like and provides also a method and apparatus bywhich the improved hobs and worms can be out accurately and the desiredcurvature of tie teeth of the work. The accompanying drawings illustratean cmbodiement of the invention. Figure 1 is a front elevation of ahobbing rapidly, the machine determinin automatica ly machine employedin cutting a worm gear;-

Fig. 9 is a side elevation of the same;

Fig. i} is e side elevation of a portion of said machine when fitted forcutting a worm or hobby means of a fly cutter or single cutter;

"F133" is a plan of a detaih partly in section;

Fig. 4 is a front elevation of Fig. 3 omitting the cutter and he work; 7

Fig. 5 is a side ation of a worm and worm gear made in accordance withthe invention;

Fig. 6 is a developed plan of one of the teeth of the worm;

Fig. '7 is a cross-section of the worm approximately on the line 77 ofFig. 5, developed reetilinearly;

'Fig. 8 is a developed pla teeth of the hob;

Fig. 9 is a horizontal section through the carriage of the machine.

The principal parts of the machine comof one of the .bined asillustrated are applicable for the cutting of all sorts of spiralthreads and gears; the two principal shafts of the machine arranged at aright angle to each other being adapted to receive, one shaft a blankand the other shaft a suitable cutter so that when the two shafts arerevolved synchronously at. the proper ratio the tool will generate aspiral cut or cuts on the work. By way of example I have illustrated themachine cutting a worm gear and cutting a worm or hob.

Referring first to Figs. 1 and 2, A-is a Specification of LettersPatent.

Patented July 9, 1918.

Application filed December 5, 1914. Serial No. 875,654.

gear B. The shank of tlie hob is mounted between a" tail stock C and ahead stock D of any usual or suitable construction carrying a shaftwhich engages the end of the hob to turn'tlie latter, said shaft bein'grotated by means of a par E on its outer end which engages a gear F on-ashaft G which carries at its outer end a large gear II engaging a gear Jwhich in turn is driven b means of a pinion K on a shaft L whic 1 runstransversely through the machine and carries a cone pulley M at itsopposite end by which it is driven. The shaft G with its gears and thegear J are carried on a plate M which is pivoted on the shaft L so as tofacilitate a change in the gears between the driving shaft L and theshaft of the head stock, as is well understood in the art.

The shaft of the head stock is indicated in'dottcd lines at E (Fig. 1).

The shaft. N which carries the worm gear B, or the blank from which suchworm gear 9) comprises a front plate with gibs on its edges for takingup wear, which front plate has a vertical movement of several inchesvctween the straps O on the front of the machine and the side frames Theworm gear 1 is fastened on the shaft by means of nuts 0 and The worm Qwhich operates the gear 1 is carried in a bracket made fast to thecarriage and 1s sphned on the shaft B so as to move up and down with thecarriage. The carriage or slide is supported by means of a. rod T, thelower end of which is screw threaded through a nut U mounted to rotatein a fixed bearing V mounted on thercar face of the front frame of themachine; the nut ll being rotatable, through beveled gears W and W, bymeans of a hand wheel X at the front of the machine.

The shaft N is first raised by means of the h d wheel and a blankapplied tn H1 she-"lit N, and a hole applied between "the stocks C .nntltl l. lllhe machine being stunted will remtetheiblank antithe hob sothat as the :fornter is lowered the hob will cutthe idesiredzepirulteeth. The depth of 'theieut. is increased gradually by the lowering ofthe worlt by nueans of the hand wheel X nntil tlw tinished depth isreached.

hor cutting a wornior a hob theblank is introdttoe'dbctwecn the stocksaUand :D and in: cutter applit-d to the endzof the shaft The cutter istl-lenln'onght downto the work and the work and cutter rotated asabovedescribed. the cutter being 'fed downward hymn-ans of the handwheel X as the depth of the cut increases.

Reterring'to the 'finishcd worm Y and gear z of l ig. arit wi l beunderstood that as the worm rotates each tooth a thereof has its forwardend thrust into a groove between two of the teeth of'thc gear. For thehighest t tlicicncy t-hctccth of'lhe worm are shaped incross-scctiontolit accurately the grooves in the gear; and similarly theteeth of the gear should lit. the grooves of the worm. This being thecase each tooth which is out of line with the entrance of its .gn'oovceven by an infinitesimal amount is liable to strike the wall of thegroove at one side or the other, opposing a certain resistance to theoperation and making a noise which should not exist in a tlu-orctitaillyperfect. gearing. In order to avoid this noise and i-uetliciency I lprefer to relieve the teeth of either the worm or the worm gear or bothby tapering them slightly as shown in Fig. ti at both ends, so that theend of each tooth will clear the walls of the groove which it isentering and will come to a full bearing against, the Walls of suchgroove gradually. The amount of relief necessary in accurately madeapparatus is very little. It is important, hmvtwer. that thispart ofthetecth should be accurately cut and that the roiiet' or taper shouldbe nicelygraduwaited and should be unitorur for all of the teeth of aworm or gear. The relief rcfcrrcd to is of particular importance in theworm since the latter is usually made of hardened stevl;w\rhcrcas theworinagonr is ordinarily of bronze or other compaimtirely softnnetal andthu ends of its.tecth soon wear to aslight. lupcr in use.

Hobs for cutting such worms, should be liuade with the ends oftheicdeethcorre upondingly llarcd, as in Fig. 8. The outlet cuch spiral tooth ot'a hob eutstherend portion of the teeth of the worm or worin gmuntponwhich itis'operaliing, niul the'intcrincso. tdiutU'IIfiBliiUII-U'f thetooth ol the-hobcntstthe intermediate portion ot-the groove in the work.Since in order to produce teeth whichnretmpered as at; n. the-groovesbetween s'lwh'llttlitll must, be flared at theends, flthehQb130Dthii\"0f F ig. 8, which cuts-such ter grooves, will produce thework, tapered tinted.

Instead of using a the desired teeth on at their ends as indihob theworm or worm gear may be cut with a single cutter as in Figs. 3 and 4,or ahob may he cut therewith, and in this connection I have illustratedan addition tolhe machine by which .it automatically and with perfectuniformity and accuracy shapes the ends of the teeth of a norm or a hobin the manner above described; or in 'fact, by the use of a suitably shawd cain, can be used to shape the teeth of the work to any one of agreat varietv of contours. In this construction the shaft is supportedin a carriage O which is vertically guided as in the previouslydescribed ct-iustruction, and is raised and lowered by means of a rod Tas before. The rod T, however, supports the carriage 0 through theit-itcriucdiation of an equalizing lever c, the rear arm of whichcarries a. pivoted saddle ll bearing against. the underside of thecarriage and the forward end of which is guided between flanges cfastened on the carriage and projecting below the same. The lever c isin two parts lying on opposite sides of the rod T, as shown in Fig. 4,and carries at its forward end a roller f adapted, when the lover israised as hereinafter described. to bear against a cam g which isinountedon the shaft. just in the rear of the tool holder it whichcarries the single cut- The hob to be cut is indicated at k. The rain iscircular throughout the greater portion of its contour and is formedwith a variation in radius along the portion of its contour n hich bearson the supporting block 7' or forward end of the lever 0 while thecutter j is in engagement with the work'k. The shape of this ell cctireportionof the ra n will dcprnd upon the character of the movementnecessary to cut the teeth of the work as desired. In the caseillustrated the cant is provided with a flat portion Z which causes thetool to enter the work with a cut of minimum depth, to cut to agradually incrcasiing depth toward the middle of the work and to cut toa gradually decreasing depth as it leaves the work. This will produce ahub with. grooves tapered at the ends in. width and with teeth llared atthe ends in width, as in Fig. 8.

The untchine is cnsilyadjustablc to secure this automatic taper on theteeth, or to he handuonly ,and to cut teeth of uni-- form width.Forthisiudjustment vitis only necessary ,to..br ing the lever 0- intoplay against. thecam, or to withdrawfthellever ifromonerativqpositionand to support the i-mrringe directly on the hand, operatedrod '1. .Asshown in Fig. 3 the lever 11 is nonnt cdeta-entrically onhits pivot pinland this pin isoprovidcd with a. handle m accessible from .Lheopen.rear of the machine. In the positlon of Fig. 3 the lever is lowered sothat the carriage rests on the.top of the rod T and the cam at allpoints clears the roller f, so that the automatic tapering action iseliminated. By swinging the handle ML to the rear, however. theeccentric portions of the pivot pin will lift the lever to first bringthe roller up against the cam and then lift the carriage off the end ofth rod snlficiently to cause the 'am to hear at all times on the roller.

The a tion of the lever r is to divide the throw of the cam so that thetotal movement of the carriage 0 and the cutter in a vert-i' caldirection will be only a determined fraction of the throw of the am.\Vhen the Hat portion l of the ram arrives at the roller f on theforward end of the lever the cam starts to fall. The falling movement ofthe cam carries with it the entire carriage which presses down the rearend of the lever 0 and lifts the roller f to meet the descending cam.Supposing the two arms of the lever r: to be of equal length. then theactual movement of the cutter would he one-half the throw of the cam.Thus any error in the contour of the cam is reduced by half, so that thegreatest precision is secured.

In cutting a worm instead of the hob k the cam will be shaped to liftthe cutter at,

the intermediate portion of its cutting movement and to lower it. at thebeginning and end of such movement so as to make .the grmivcs in thework flare toward the ends and the teeth taper toward the ends.

The cutter j is of sufficient de th to clear the outer edges of theteeth of t e work, as indicated in Fig. 7, so that it does not alter theradial depth of such'teeth from end to end, but only takes off a greateror less portion of the metal from the sides of the teeth. This mechanismfor val-yin the width of the cut has the advantage 0 preserving theradius of rotation of the cutter uniform at all times, since its axis ofrotation rises and falls. As the rate of rotationof this shaft isconstant, it follows that the linear velocity of the cutter is constantand as it moves across from end. to end it cuts a groove which, thoughflared at the ends, has its center line on a trne 'spiral,a point ofgreat importance in securing etiiciency and .smooth rmming of the worm.

The multiple thread or mutiple toothed worm of Fig. 5 should be cut, forspeed, with a hob or cutter having the same number of teeth. These toolsmay be developed from the fly cutter and apparatus of Fig. 3 in thefollowing manner: The ratio between the rates of rotation of the hub isand the cutter head hshould be 'incommensurable so that .the cutter inits'successive engagements with the work will cut first one andthenanother I of the teeth. For example, the parts may he so gearedas tomake four. turns of the eutter head to thirty-nine turns of the worm, orone to nine and tln'ce-quarters. Because of the fractional relation anycertain tooth of. the work would be operated on by. the cutter only oncein each fourth revolution of the latter. in this way a four-tooth hobwould be generated. Working bacluvard from this hob on the same machinea cutter, the blank being mounted on the shaft could be generated havingthe number of teeth desired. and this cutter could in turn be used togenerate worms of the same dimensions as the hob originally produced by,the single cutter.

Though have described with great particularity of detail certaincmlmdiments of my invention yet it is not to be understood therefromthat the invention is restricted to the particular embodimentsillustrated. Various modifications thereof within the scope of theappended claims may be made bv those skilled in the art withoutdeparture from the invention. The worm and the cutter described aboveare not claimed in the present application, but. it is not to heinferred therefrom that I thereby waive my right to claim the same in aseparate appli cation.

What I claim it.

1. A machine for cutting hobs, worms or the like adapted to revolve thecutter and the work on axes at an angle to each other so' as to. causethe cutter to make a spiral cut inthc work, said machine including meansfor automatically sl'iifting one of said axes towaul HIIJ aivavfrom theother during the engagement of the cutter with the work.

2. A machine for cutting hobs, worms or the like adapted to revolve thecuttter and the work on axes at an angle to each other so as to causethe cutter to make a spiral cut in the work, said machine includingmeans for automatically shifting one of said axe toward and away fromthe other during the engagement of the cutter with the Work, said cutterbeing. tapered and shaped so as to clear the outer edge of the teeth atall times, whereby said movement of the axes results in .a variation ofthe width of thev teeth without variation'of their depth.

3. A machine for cutting hobs. worms or the like adapted to revolve thecutter and thework on axesat an angle to each other.

so as to cause the cutter to make a spil'ul'cut in the work, saidmachine including a rota-ting cam hv which one of said axes is movedtoward and from the otherilm'ing the engagement of the cutter with thework.

4. A machine for, cutting hobs, worms or the like adapted to revolve thecutter and the work on axes at an angle to each other so as to cause thecutter to make a spiral cut in the work, said-machine comprising incombination shafts arranged on the said axes, a carriage in which one ofsaid shafts is carried, supporting means for said ourriage and means formoving said carriage toward and from the other shaft as its shaft isrotated.

5. A machine for cutting hobs, worms or the like adapted to revolve thecutter and the work on axes at an angle to each other so as to cause thecutter to make a spiral cut in the work, said machine comprising incombination shafts arranged on the said axes, a carriage in which one ofsaid shafts is carried, supporting means for said carriage and anequalizer between said carriage and said supporting means to permit the'arriagc to be moved with a parallel movement relatively to thesupporting means.

6. A machine for cutting hobs, worms or the like adapted to revolve thecutter and the work on axes at an angle to each other so as to cause thecutter to make a spiral cut in the work, said machinecomprising incombination shafts arranged on the said axes, a carriage in which one ofsaid shafts is carried, supporting means for said carriage, anequalizing lever carried by said supporting means and engaging saidcarriage at one end and, a cam mounted on the shaft within said carriageand. adapted to engage the other end of said lever.

7. A machine for cutting hobs, worms or the like adapted to revolve thecutter and the work on axes at an angle to each other so as to cause thecutter to make a spiral cut in the work, said machine comprising incombination shafts arranged on the said axes, a carriage in which one ofsaid shafts is carried, supporting means for said carriage, an equalizerbetween said carriage and said supporting means to permit the carriageto be moved with a parallel movement relatively to the supporting meansand means for shifting said equalizer to an inoperative position.

8. A. machine for cutting hobs, Worms or the like adapted to revolve thecutter and the work on axes at an angle to each other so as to cause thecutter to make a spiral out in the work, supporting means for saidoutter, a cam by which one of said axes is moved toward and from theother during the engagement of the cutter with the Work, and means fordividing the throw of the cam so that the total movement produced willbe only a determined fraction of such throw.

9. A machine for cutting hobs, worms or the like adapted to revolve thecutter and axes, a carriage in which one of said shafts is carried,supporting means for said carriage, an equalizing lever 0 carried by thesummrting means and engaging said carriage at its rear end, a cam 9carried near the forward end of the shaft in said carriage and adaptedto engage the forward end of said lever, whereby as the shaft in saidcar riage rotates the carriage is lifted and lowercd relatively to itssupporting means by an amount. less than the throw of the cam.

10. A machine for cutting hobs, worms and the like comprising a taperedcutter having a uniform linear velocity, means for generating a relativespiral movement between the cutter and the work, and means for effectinga relative movement of the cutter toward or away from the work during acutting operation so as to produce a tooth of varying width at differentpoints in its length.

11. A machine 'for cutting hobs, worms and the like comprising a cutter,means for generating a relative spiral movement between the cutter andthe Work, and means for effecting a relative movement of the cuttertoward or away from the work during a cutting operation whilemaintaining a constant relative linear velocity of the cutter.

12. The method of cutting hobs, worms, and the like which consists ingenerating a relative movement between an oblique cutting edge and thework in the direction of the desired tooth and effecting a relativemovement of the cutting edge toward or away from the work during acutting operation ,while maintaining a constant relative linear velocityof such cutting edge.

13. The method of cutting hobs, worms and the like which consists ingenerating a relative spiral movement between an oblique cutting edgeand the work and effecting a relative movement of the cutting edgetoward or away from the work during a cutting operation whilemaintaining a constant relative linear velocity of such cutting edge.

In, witness whereof, I havehereunto signed my name in the presence oftwo subscribing witnesses.

WILLIAM OANNELL. Witnesses:

THEO. W. ELI-1B, ELIBHA H. Bxnws'mn.

